Form and function are intimately interrelated. However, the histological analyses of our target tissues (bone, cartilage, tendon, ligament, muscle) provide specialized challenges not often encountered when conducting these techniques on non-skeletal tissues. For example, due to the extensive extracellular matrix, these tissues can be very difficult to prepare and section, and bone presents a particular challenge due to mineralization. A specialized knowledge of the stages of development, and limb and joint morphology is necessary for the analysis of skeletal tissues. In addition to morphology, the localization of proteins and mRNA in mouse models of musculoskeletal diseases is a vital component in the analysis of the molecular mechanism of protein function, the response to injury, and disease. The overall objective of the In situ Molecular Analysis Core is to provide histological services for the identification and analysis of molecular phenotypes of our target tissues, bone, cartilage, muscle, tendon and ligament, in developing and adult mice. The services will include preparation of tissues and tissue sections;a reagent bank for histology, immunohistochemistry and in situ hybridization;and training in the techniques of in situ hybridization to mRNA, immunohistochemistry, deconvolution microscopy, and histomorphometry. Reagents for the analysis of mouse, and in some cases human, tissues will be available. We expect that the findings from mouse models will be extended to human disease and injury. The Director/Co-Directors and collaborating investigators will provide consultation and advice on analysis and interpretation of the target tissue phenotypes. Deconvolution microscopic analysis and bone histomorphometry will provide the opportunity to utilize sophisticated techniques and quantitative analysis not currently available to all investigators. The strength of this Core lies in the specific techniques developed for adult mice, sectioning delicate early healing tissue, and properly aligning blocks for sectioning of ligament and fracture healing, as well as the expertise in tissue staining by a wide variety of histochemical and molecular techniques. All aspects of the core provide collaboration, training, and education, which will strengthen ties among the research base and enhance the quality of the science performed. Thus, not only will this Core be cost-effective, it will allow scientists to explore skeletal phenotypes that they could not in any other way investigate. This core will complement the specific functional analyses proposed in Core B and the mouse models of Core D.